The face that launched a thousand ships

What's the meaning of the phrase 'The face that launched a thousand ships'?

A reference to the mythological figure Helen of Troy (or some would say, to Aphrodite). Her abduction by Paris was said to be the reason for a fleet of a thousand ships to be launched into battle, initiating the Trojan Wars.

What's the origin of the phrase 'The face that launched a thousand ships'?

Christopher Marlowe, in Doctor Faustus (variously dated between 1590 and 1604), referring to Helen of Troy, or as Marlowe had it 'Helen of Greece':

Was this the face that launch'd a thousand ships
And burnt the topless towers of Ilium?
Sweet Helen, make me immortal with a kiss.